I’m using a particle system to place rocks on a terrain. Despite playing with every setting I could think of to resolve the problem, I can’t stop many of the rocks from floating above the ground. The particles are last in the modifier list, and I even have “use modifier stack” enabled in the particle emission settings to guarantee the updated geometry should be used.
I believe this occurs most when child particles are used. I'm using interpolated children which to my knowledge are aligned to the mesh surface thus shouldn't be producing this problem. I need child particles as they're the only way to achieve proper clumping (groups of little rocks scattered in various points), if I use just parent particles each individual rock is placed at random without any pattern.
Also please don't direct me to use geometry nodes: I'm aware they exist and they're definitely an exciting feature, however the latest implementation is still in early stages and constantly changing around a complex attribute setup. Once it becomes reliable I may go for those nodes, but in the meantime I'm still using particles for terrain details such as grass.
Here's a simplified version of my blend containing just the terrain with particle rocks. As can be seen in the screenshot the rocks tend to float quite a bit above the surface.